Board Thread:General Discussion/@comment-34731221-20180224060844/@comment-27248965-20180226033457

It depends on Pokemon species. For example, in B/W/B2/W2 (Unova), Audino in the rustling grass was a rather popular way to train because it gave plenty of EXP. However, we don't have a Trainer available of rematches with a team of Chansey family or Audino for now. You'll just have to stick with Beach Bum Joe on Decca Beach if you want to rack up EXP quickly with your Pokemon.